The world is watching as Congress considers possible U.S. military action in Syria. And few countries are more concerned than nearby Israel where one worry is that the Syrian conflict could spill over.

As NPR's Emily Harris reports, Israelis are sure they want the U.S. to do something in Syria. They're less clear about just what it should be.

EMILY HARRIS, BYLINE: Retired Lieutenant Colonel Mickey Segall doesn't know the best recipe for a U.S. airstrike in Syria.

MICKEY SEGALL: You know, you put five tomahawks to the left, two tomahawks to the right and one Tomahawk to the middle, I don't know. I think the United States and its allies must come with something very creative, something that will help restore the American deterrence power in the Middle East.

HARRIS: And what mostly needs deterrence, Segall says, is Iran. Segall has tracked Iran closely for decades, first in the Israeli military, now for Terrogence, a private Israeli company offering intelligence services to governments and corporations.

SEGALL: We all look at the Iranian from the nuclear aspect. But Iran is more dangerous.

HARRIS: Segall says Iran's long-term goal is to spread its particular brand of Shiite Islam and its anti-Israel message around the Middle East. Many Israeli government officials want the U.S. to respond strongly against Bashar al-Assad's alleged use of chemical weapons, in part to show Iran what to expect if it continues to develop nuclear weapons.

David Horovitz, founding editor of The Times of Israel, says that's important.

DAVID HOROVITZ: If you're not going to stand up urgently to a Syrian president killing his own people with nerve gas, what does that say to the Iranians as they close in on a nuclear weapons capability?

HARRIS: He says Obama's decision to delay a strike while consulting with Congress has left Israel feeling on its own.

HOROVITZ: I'm not saying that I think the United States would necessarily let Israel down in an existential struggle. But episodes like this certainly underline the conviction that, you know, it is possible that when all else, you know, when all else fails, at a last resort, Israel needs certainly to be able to take care of itself, by itself.

HARRIS: The government is making gas masks available to Israeli citizens. Some Israelis worry that Damascus or its allies may target Israel after any U.S. strike on Syria.

At a community center near Tel Aviv, the wait to pick up a gas mask dropped this week from eight hours to only a few minutes. Amberleah Centner came in to get one just in case. She doesn't know what she wants the U.S. to do in Syria.

AMBERLEAH CENTNER: It's kind of a lose-lose because on the one hand, all right, we'll take care of the threat at moment, and then we'll be thrust into another war over here. Then on the other hand, if we don't take care of the threat at the moment, we might have a war anyway down the line, and it'll be worse.

HARRIS: Igal Galperin was also at the distribution center. He says the U.S. should put troops on the ground.

IGAL GALPERIN: I think it's not enough to send some missile. It's supposed to be a ground attack and clean all old regime and put a new one.

HARRIS: Some Israeli observers draw lessons from Iraq, saying they'd like Assad out but his Ba'ath Party structure to remain as a form of stability. Middle East security analyst Yiftah Shapir says Israel still isn't sure what the best outcome would be in Syria.

YIFTAH SHAPIR: Certainly not Bashar al-Assad, but certainly we don't want al-Qaida or the Muslim Brotherhood or any Sunni extremists. I don't think an American intervention, at least the type that is envisioned right now, would change anything to Israel.

HARRIS: President Obama's delay gave Israelis time to mark the Jewish New Year this week without a focus on war. One New Year's blessing over beets uses a play on words in Hebrew to wish all enemies away.